Evolution and humans: big brain size uses energy (Evolution)

by dhw, Thursday, November 02, 2017, 12:59 (445 days ago)@ David Turell

DAVID: The ability to have upright posture preceded the descent from the trees. Lucy walked upright but still had long muscular arms to show she also used the trees.
dhw: Perhaps when her species left the trees and began to walk upright, their long arms were still useful and enabled them to continue spending time in the trees. Isn’t this just as likely as your God suddenly dabbling with a bunch of apes up in the trees, fiddling with their bodies, and telling them to go walk on the ground except when they felt like going back up the trees?
DAVID: That comment agrees with my concept. Of course they used the trees and ground at first with their changed bodies.

There is no agreement. My concept is that they descended from the trees, which led to their upright posture, though they retained their long arms. Yours has God preprogramming or dabbling the changes before they descend. The concepts are directly opposed.

DAVID: […] the only event we know of in intense use of a brain is shrinkage. You are extrapolating in the opposite direction with no evidence.

You continue to ignore the other event we know of, which is that the brain complexifies (rewires ) IN RESPONSE to new tasks imposed on it (e.g. the illiterate Indian women who learned to read). Shrinkage would have begun after the brain had reached optimum size, and complexification had taken over.

DAVID: “…expanding hominid brains before there is any reason for them to be expanded" is God allowing them to get to a more advanced mental status.
dhw: An extraordinary claim for a dualist, who believes that the mental state does NOT depend on the brain.
DAVID: I'll go back to computers: an advanced computer allows production of advanced artifacts, which a lesser computer cannot. The soul uses the early brain to create complexity as far as that brain allows. With the soul in charge the next more complex brain allows more complex creations. Yes, it is the other way 'round from you.

Your computer analogy clearly showed that advanced computers were designed IN RESPONSE to the need for more complexity, not in anticipation of such a need. Your dualistic “soul” does indeed use the brain to implement its ideas. If the existing brain does not allow implementation, then it needs to expand (former times) or complexify (modern times). Why would it expand/complexify in anticipation of ideas that have not yet been thought of?

DAVID: In my view God creates advances by 'suction' pulling advances forward by design. You believe in 'pushing' from behind. Two very different interpretations which will not be resolved, since you are so fixed upon avoiding God as a necessary designer.
dhw: At no time have I ever offered any hypothesis that does not include the possibility of God as a designer. I am not an atheist. You reject my theistic hypothesis because you are “fixed upon” a personal interpretation of your God’s intentions, even though it does not explain most of evolution’s history.
DAVID: Thanks again for offering God lite, and my theory does provide for the bush of life.

I don’t know what you mean by God lite. A God who invents a mechanism that creates an evolutionary free-for-all with the option of the occasional dabble is just as much a God as one who designs every single innovation, lifestyle and natural wonder so that he can have a relationship with one particular species.

DAVID: Yes, environmental changes foster epigenetic adaptations. Species change require advanced planning and is a process we do not understand. but it is obvious planning and design are required. Again we have two very different views of the requirements for new species to appear. It cannot be a bit-by-bit stepwise process. The fossils do not show it as Gould repeatedly pointed out.
dhw: My hypothesis allows for saltations as well as “bit-by-bit” processes such as the eight-stage whale and the multi-staged history of hominins, hominids and humans.
DAVID: Bit-by-bit only implies tiny changes, adaptations not speciation!

You have quoted me above: my hypothesis allows for saltations as well as “bit-by-bit”.

DAVID: Environmental changes are only one of many reasons for speciation. Speciation is planning in advance. Epigenetic modifications are not speciation.

NOBODY knows how speciation occurs, and I keep agreeing that epigenetic modifications are not speciation. But they are proof that there is an autonomous mechanism which can change the bodies of organisms. The question is whether it is capable of major innovations as well as minor changes. Speciation (broad sense) is not planning in advance. Speciation is major changes to the anatomy. It is you who insist that they must be planned in advance, as opposed to being responses to the challenges and opportunities offered by the conditions in which organisms find themselves.